The manufacture of many fermented food products, such as cheese, buttermilk, sour cream, yoghurt and the like, requires the use of starter cultures, i.e. a concentrated microbial biomass, as described in U.S. Pat. Nos. 3,159,490 and 4,115,199. These starter cultures can be prepared by a well-known method which involves culturing the microorganism in a nutrient broth to produce a desired cell population and then recovering the cell biomass from the broth by centrifugation (J. of the Society of Dairy Technology 30, 36[1977]). To facilitate handling and sample uniformity, it is desirable that the recovered biomass having an effective microbial cell population, usually greater than about 1.0.times.10.sup.8 colony forming units (CFU)/ml, be contained in a packed cell volume of less than about 5% on a volume/volume basis based on the total volume of the culture broth.
Some types of microorganisms, however, which grow in long filaments or chains of cells, for example about 15 to 30 cells in length, form a loosely packed or flocculant biomass which is difficult to concentrate and inefficient to recover by centrifugation. This flocculant biomass inefficiently fills the holding area of the centrifuge thus resulting in considerable loss of the biomass to the effluent stream and reducing the yield of the recovered biomass.